System for accurate 3d modeling of gemstones

ABSTRACT

A computerized system, kit and method for producing an accurate 3D-Model of a gemstone by obtaining an original 3D-model of an external surface of the gemstone; imaging at least one selected junction with only portions of its associated facets and edges disposed adjacent the junction, the location of the junction being determined based on information obtained at least partially by using the original 3D model; analyzing results of the imaging to obtain information regarding details of the gemstone at the junction; and using the information for producing an accurate 3D-model of said external surface of the gemstone, which is more accurate than the original 3-D model.

FIELD OF THE DISCLOSED SUBJECT MATTER

The disclosed subject matter pertains to the measurement of gemstones,more particularly, to the computer-aided 3D modeling of gemstones.

BACKGROUND OF THE DISCLOSED SUBJECT MATTER

It is known how important accurate 3D modeling of gemstones,particularly, diamonds, is for allowing diamond manufacturers,wholesalers and gemologists to evaluate the diamonds' proportions, itsdimensions as well as its symmetry, inter alia, for the purpose ofgrading the stones.

WO 99/61890 discloses a method and associated apparatus for measuring agemstone for its standardized grading. The system gauges the spectralresponse of a gemstone subject to a plurality of incident light sourceswithin an imaging apparatus. The operation of the imaging apparatus iscontrolled by an instruction set of a local station control dataprocessor.

U.S. Pat. No. 7,259,839 discloses a method of measuring a physicalcharacteristic of a facet of a diamond, in particular its edges, andobtaining a 3D model thereof including such edges.

SUMMARY OF THE DISCLOSED SUBJECT MATTER

In accordance with one aspect of the presently disclosed subject matter,there is provided a computerized method for producing an accurate3D-Model of a gemstone comprising:

-   -   a) obtaining an original 3D-model of an external surface of said        gemstone, said surface including facets, edges abounding said        facets, and junctions each constituting an area of meeting of at        least three said edges associated with at least two facets;    -   b) imaging at least one selected junction of the gemstone with        only portions of its associated facets and edges disposed        adjacent the junction, the location of said junction being        determined based on information obtained at least partially by        using the original 3D model, said imaging being performed under        at least one imaging condition different from that at which the        original 3-D model was obtained, and under illumination        conditions providing such contrast between adjacent facets as        allow to distinguish an edge therebetween;    -   c) analyzing by the computing system results of said imaging to        obtain information regarding details of the gemstone at said        junction; and    -   d) using by the computing system the information obtained in        step c) for producing an accurate 3D-model of said external        surface of the gemstone, which is more accurate than the        original 3-D model.

The above method of accurate 3D modeling a gemstone is particularlyadvantageous for modeling cut gemstones, such as for example, polishedand semi-polished diamonds, since it allows a much higher accuracy ofdetermination of cut and symmetry parameters of the stones than thatprovided by conventional 3D modeling techniques, by which the original3D model can be obtained.

In particular, the above method allows for determination of facetmisalignments and more accurate locations and geometry of junctions,compared with the original 3D model, revealing extra edges, facets andjunctions not revealed in the original 3D model, as well as superfluousedges, facets or junctions, which were erroneously recorded whenproducing the original 3D model; thereby the capability of performingfast, accurate and repeatable grading of the stones can be essentiallyimproved, allowing their more objective and more complete certificationand—not less importantly—replacing a manual observation by trainedgemologists.

Accurate 3D models obtained by the above method can also be used for anyother relevant purposes, such as for example: facilitating uniquefingerprinting of a stone for any relevant purpose requiring itsauthentication, and generating high-accuracy ray-traced virtual modelsthereof, which is particularly advantageous for trading diamonds viae-commerce, to provide higher confidence with regards to their actualappearance.

The method according to the presently disclosed subject matter cancomprise performing the steps (b) to (d) above for all junctionsrevealed in the original 3D model and also, in case the stone is a cutstone, for all non-revealed junctions existing in a predicted/plannedgeometry of the stone, but absent from said 3D model. Regarding theplanned geometry, it is the one, according to which it was supposed tobe cut. In connection with predicted/planned geometry, it is defined bya style used when shaping a diamond for its polishing, such as forexample, the brilliant cut. The cutting style does not refer to shape(pear, oval), but the symmetry, proportioning and polish of a diamond.The most popular diamond cutting style is the modern round brilliant,whose facet arrangements and proportions have been perfected by bothmathematical and empirical analysis. Also popular are the fancy cuts,which come in a variety of shapes-many of which were derived from theround brilliant.

The method can also reveal erroneously recorded junctions, i.e. thosethat were recorded in the original 3D model, but do not exist in thereal cut stone.

The method can also comprise obtaining a plurality of images of the oreach selected junction and selecting thereamongst at least one selectedimage, in which one or more edges seen therein are distinguished overthe remainder of the image better than in other images.

The method according to the presently disclosed subject matter can alsobe used to accurately determine the geometry of the stone's girdle andother girdle features such as naturals, extra facets and the like, andthereby generate a more complete accurate 3D model of the stone. In thisconnection, it should be explained that naturals are areas of theexternal surface of a cut stone, which have not been polished but ratherhave been left as they existed in the rough stone, from which the cutstone was shaped for polishing. Extra facets are those that have beencut/polished without them being a part of the planned geometry.

For this purpose, the method according to the presently disclosedsubject matter can comprise obtaining one or more images of as manyselected portions of the girdle as desired, said one or more imagesbeing taken under such conditions as to enable distinguishing at leastone planned feature at the or each said selected portion of the girdle;analyzing said one or more images to obtain information regardingdetails of the girdle at said selected portion thereof; and using saidinformation in generating said accurate 3D-model. The selected portionscan be chosen based on the original 3D model or based on any otherconsideration, and this can be done so that the whole girdle is imaged.

If the analysis of the images of the girdle results in the determinationof a new girdle feature, such as an extra facet and/or natural, saidinformation in step (h) can include information regarding at least onenew girdle feature absent from the planned girdle geometry; and saidpresenting in step (i) can include adding a representation of said atleast one new girdle feature to the girdle in the accurate 3D model ofthe stone. Said representation can be a graphical representation addedat the corresponding position on the girdle in the accurate 3D model ofthe stone, e.g. by drawing borderlines of the new feature, and evenadding thereto the graphical representation of its appearance as itappears in a corresponding image.

For example, the selection can be based on the determination orprediction of some new girdle feature absent from the original 3D modeland from planned girdle geometry, based on the information obtained fromthe analysis of said one or more images, subsequently identifying aportion of the girdle comprising said new girdle feature and performingfurther steps with respect to this portion of the girdle constitutingsaid selected portion.

The method according to the presently disclosed subject matter canfurther comprise predicting a new junction absent from the original 3Dmodel and from the planned geometry of the stone, based on theinformation obtained in the relevant steps described above; consideringsaid new junction to be a selected junction and performing above steps(b) to (d) with respect thereto. When a new edge is determined, which isabsent from the original 3D model, said predicting is performed byassociating said new junction with a predicted end of the new edge atits predicted intersection with an edge revealed in said original 3Dmodel.

When, based on the information obtained in the above described method,it is realized that at least one revealed edge present in the 3D modelis missing from an image of its associated junction, such missing edgeis not included in the accurate 3D model generated by the method.

As mentioned above, the conditions at which the gemstone is imaged forgenerating its accurate 3D model are different from those, at whichimages of the gemstone are taken for generating its original 3D model.This difference can be, for example, in at least one of themagnification and resolution, which in the ‘accurate’ imaging is higherthan that, at which the original 3-D model was obtained; or in the depthof focus, which in the ‘accurate’ imaging can be lower than that, atwhich the original 3-D model was obtained.

In the above described method, the following steps can be performed forgenerating the original 3D model of the gemstone (step (a) above):

-   -   illuminating the gemstone by means of one or more step-(a)        illumination device,    -   imaging the gemstone by means of a step-(a) imaging device, and    -   rotating the gemstone relative to the step-(a) illumination        device and step-(a) imaging device to obtain a plurality of        images, based on which said original 3D model is calculated.

For performing the ‘accurate imaging’ (in step (b) above), one or morestep-(b) illumination devices can be used to illuminate the gemstone,and different portions of the gemstone are imaged by means of a step-(b)imaging device, and wherein at least one of the following conditions isfulfilled:

-   -   at least one of said step-(b) illumination devices provides        illumination different from that of said step-(a) illumination        device, and    -   said step-(b) imaging device is different from said step-(a)        imaging device.

The gemstone can be illuminated by means of one or more step-(b)illumination devices with such an illumination that at least threeadjacent facets of the crown or the pavilion, or two facets of the crownor the pavilion and the girdle, are each at least partially illuminatedwith such a contrast between at least one couple of their adjacentilluminated surfaces as to enable distinguishing an edge therebetween.Such contrast can be obtained by at least one of the following:

-   -   said illumination being uniformly diffusive along the entire        field of vision of an imaging system used in step (b);    -   said illumination having a chief ray with an angle of incidence        selected based on an average between angles defined by said at        least three facets or two facets and the girdle, with said axis        Z;    -   said illumination being provided by an illumination source using        contrast improving techniques optionally comprising a mask        interacting differently with light exiting from said        illumination source at different surface portions of said mask,        including at least one of the following:        -   at least two surface portions with distinct absorption            properties,        -   at least two surface portions with different polarization            properties, and        -   at least two surface portions that provide different            propagation properties of the light.

The number of the above surface portions can correspond to the number offacets in the field of vision.

According to a further aspect of the presently disclosed subject matter,there is provided a system configured for producing an accurate 3D-Modelof a gemstone by the method described above.

In accordance with a still further aspect of the presently disclosedsubject matter, there is provided a computerized system forautomatically producing an accurate 3D-model of a gemstone, comprising

-   -   a 3D modeling system configured for obtaining an original 3D        model of an external surface of a gemstone, including facets,        edges abounding said facets, and junctions each constituting an        area of meeting of at least three said edges associated with at        least two facets;    -   an illumination and imaging system configured for imaging at        least one junction selected from the junctions in said 3D model,        with only portions of its associated facets and edges disposed        adjacent the junction, under at least one imaging condition        different from that at which the original 3D model was obtained,        and under illumination conditions providing such contrast        between adjacent facets as to allow to distinguish an edge        therebetween; and    -   a computing system configured to analyze results of said imaging        to obtain information regarding details of the gemstone at said        junction and to use the obtained information for producing an        accurate 3D-model of said external surface of the gemstone,        which is more accurate than the original 3-D model

In accordance with a still further aspect of the presently disclosedsubject matter, there is provided method of upgrading a first systemconfigured for obtaining an original 3D model of an external surface ofa gemstone, in order to provide a second system for producing a moreaccurate 3D model of the external surface of said gemstone than theoriginal 3D model; said method comprising the steps of:

-   -   adding to said first system a second illumination system and a        second imaging device configured for imaging at least one        junction with only adjacent portions of its associated facets        and edges, the location of said junction being determined based        on information obtained at least from the original 3D model,        said imaging being performed with at least one imaging condition        being different from that or those at which the original 3-D        model was obtained, and under illumination conditions providing        such contrast between adjacent facets as allow to distinguish an        edge therebetween; and    -   adding computing capability for:        -   analyzing said images to obtain information regarding            details of the cut gemstone;        -   using said information for obtaining said more accurate            3D-model of the external surface of the gemstone.

Said imaging condition can be at least one of the following:

-   -   a magnification higher than that provided by an imaging device        with which the original 3D image has been obtained;    -   a resolution higher than that provided by the imaging device        with which the original 3D image has been obtained; and    -   a depth of focus lower than that provided by the imaging device        with which the original 3D image has been obtained.

In accordance with a further aspect of the invention, there is provideda system

In accordance with a still further aspect of the present invention,there is provided a kit for upgrading a first system configured forobtaining an original 3D model of a gemstone, in order to obtain asecond system for producing a 3D model of said gemstone which is moreaccurate than the original 3D model, said first system comprising afirst set of gemstone holders each having a first gemstone mountingsurface, a first illumination source and a first imaging device, saidkit comprising at least the following:

-   -   at least one second illumination source different from the first        illumination device; and    -   a second imaging system different from the first imaging system.

The kit can further comprise a second set of gemstone holders eachhaving a second gemstone mounting surface and being configured formounting on a stage base such so as to allow an access of said secondillumination source to a space between said second gemstone mountingsurface and the stage base.

Alternatively, the kit can comprise means configured to use the firstset of gemstone holders in such a way as to allow an access ofillumination from said illumination source to a space below between saidfirst gemstone mounting surface.

The kit can further comprise a non-transitory computer readable storagemedium comprising computer readable program code embodied therein, thecomputer readable program code causing the system for accurate 3Dmodeling of gemstones to operate as detailed herein.

Additional possible features of different aspects of the presentlydisclosed subject matter are presented in the detailed description ofembodiments and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the subject matter that is disclosedherein and to exemplify how it may be carried out in practice,embodiments will now be described, by way of non-limiting example only,with reference to the accompanying drawings, in which:

FIG. 1A is a schematic perspective view of a system for producing anaccurate 3D-model of a gemstone, in accordance with one example of thepresently disclosed subject matter;

FIG. 1B is a perspective view of a stage and the crown illuminationdevice of the system shown in FIG. 1A;

FIG. 2A is a side view of the system shown in FIG. 1A, seen facing theX-axis;

FIG. 2B is a schematic partial side view of the system of FIG. 1 a,showing its pavilion illumination device;

FIG. 2C is a schematic partial side view of the system of FIG. 1A,showing its crown illumination device;

FIG. 2D is a schematic partial side view of the system of FIG. 1A,showing one example of its girdle illumination device;

FIG. 2E is a schematic partial side view of the system of FIG. 1A,showing another example of its girdle illumination device;

FIG. 3 shows a schematic view of different gemstone holders withgemstones of different sizes mounted thereon for producing theiraccurate 3D-models by the system shown in FIG. 1A;

FIG. 4 is a schematic view of a gemstone mounted on a support surface ofone of the holders shown in FIG. 3;

FIG. 5 is a schematic view of one example of a mask, which can be usedin one of the illumination devices of the system shown in FIG. 1A;

FIGS. 5A to 5C show a flow chart of a process according to one exampleof the currently disclosed subject matter;

FIGS. 6A and 6B and FIGS. 6C and 6D are schematic representations of twoexamples of portions of original and accurate 3D models of a gemstone,respectively, produced in the framework of a method according to oneexample of the presently disclosed subject matter;

FIG. 6E schematically illustrates an exemplary image of one surfaceportion of the gemstone obtained within the framework of a methodaccording to one example of the presently disclosed subject matter;

FIG. 7A to 7D schematically illustrate, in perspective and side views, aprocess of upgrading an original 3D modeling system (FIG. 7A, 7C) toobtain a system (FIG. 7B, 7D) for producing an accurate 3D-model of agemstone, in accordance with one example of the presently disclosedsubject matter.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1A schematically illustrates one example of a system 10 forproducing an accurate 3D model of an external surface of a gemstone Gcut in accordance with planned cut geometry to have a crown, a pavilion,a girdle and a table, the crown and the pavilion having planned facets,edges abounding the facets, and junctions, each constituting an area ofmeeting of at least three such edges associated with at least twofacets.

Whilst the gemstone's planned cut geometry is known, the gemstone's realgeometry and, particularly, the geometry of its pavilion, crown andgirdle is what the system 10 is aimed to determine with a high accuracy,by:

-   -   obtaining an original 3D-model of said gemstone,    -   imaging junctions with only adjacent portions of their        associated facets and edges, the junction's location being        determined based on information obtained at least partially by        using the original 3D model, with at least one of magnification        and resolution being higher and/or depth of focus being lower        than those at which the original 3-D model was obtained, and        under conditions providing such contrast between adjacent facets        as allow to distinguish an edge therebetween; and    -   analyzing results of the above imaging to obtain information        regarding details of the gemstone at said junctions; and using        this information for producing a new 3D-model of the gemstone        which is more accurate than the original 3-D model.

In the currently disclosed example, a brilliant-cut diamond isconsidered as the gemstone to be modeled, though this is a purelyexplanatory necessity, and there may be a number of possible gem cutgeometries that can be analyzed by the currently disclosed system. Infact, any cut of a gemstone can be modeled by the system, as long as itoffers one resting surface, on which the gemstone can be placed for theanalysis.

With reference to FIGS. 1A, 1B the system 10 comprises a stage station30 for supporting the gemstone G, a first 3D modeling system 60 with afirst optical axis FOA, for producing an original 3D model of thegemstone, and a second 3D modeling system with a second optical axisSOA, for producing an accurate 3D model of the gemstone at an augmentedaccuracy level compared to that of the original 3D model.

The stage station 30 and the first and second 3D modeling systems areall fixedly mounted on a system base 12, with a system cavity 15 formedtherebetween, configured for receiving therein the gemstone G supportedat its resting or mounting surface S (see FIG. 4) by the stage station30 so as to allow to both 3-D modeling systems to have an optical accessto any surface of the gemstone except for its resting surface, withoutremoving the gemstone from the stage station.

The first and second 3D-modeling systems 60 and 100 are mounted on thebase such that the spacial relationship of the first optical axis FOA tothe base 12 remains constant, while the second optical axis SOA can moveduring operations of the system, as described in further detailhereinbelow.

It has to be stressed, that the disposition of the second 3D modelingsystem 100 relative to the first 3D modeling system 60 as shown in thisexample is purely by way of a non-binding, explanatory exposition forthe purpose of understanding the herein disclosed subject matter, andthat any other relative disposition of the 3D modeling systems inrelation to each other is entirely possible.

The system 10 further comprises a computer system 300 comprising aprocessor (not shown) operatively coupled to a memory (not shown)storing appropriate software and a control card 310, which is soconnected to the above system's components on the one hand, and thecomputer system 300 by way of connection line 223 on the other, as toallow for necessary controlling all their operations.

Unless specifically stated otherwise, as apparent from the followingdiscussions, it is appreciated that throughout the specificationdiscussions utilizing terms such as “processing”, “computing”,“calculating”, “generating”, “configuring”, “controlling”, “choosing”,“building”, “deciding” or the like, refer to the action and/or processesof a computer that manipulate and/or transform data into other data,said data represented as physical, such as electronic, quantities and/orsaid data representing the physical objects. The term “computer” shouldbe expansively construed to cover any kind of electronic device withdata processing capabilities including, by way of non-limiting example,the computing system 300 disclosed in the present application.

The computerized operations in accordance with the teachings herein maybe performed by a computer specially constructed for the desiredpurposes or by a general-purpose computer specially configured for thedesired purpose by a computer program stored in a computer readablestorage medium.

Embodiments of the presently disclosed subject matter are not describedwith reference to any particular programming language. It will beappreciated that a variety of programming languages may be used toimplement the teachings of the presently disclosed subject matter asdescribed herein.

It is noted that the control card 310 can be integrated with thecomputer system 300. Additionally or alternatively, the functions of thecontrol card (or part of them) can be distributed between all or some ofthe components of the system 10.

The system's components will now be described separately in more detailwith reference to the corresponding drawings.

The Stage Station 30

With reference to FIGS. 1A and 1B, the stage station 30 comprises:

-   -   a replaceable gemstone holder 31; and    -   a stage base 42 with a drive stepper motor 43 so as to be        rotatable by the motor 43 about an axis of rotation RA.

The stage base 42 has a holder mounting surface 42 a, at which thegemstone holder 31 is mounted, disposed at a constant height relative tothe system base 12. The first optical axis FOA of the first 3-D modelingsystem 60 intersects with the axis of rotation RA at the origin of therelative Cartesian coordinate system RCCS of the system 10, the X-axiscoinciding with the FOA and the Z-axis coinciding with the RA.

The replaceable gemstone holder 31 comprises:

-   -   a holder base 32 with a holder base upper surface 32 a and a        holder base lower surface 32 b; and    -   a tower stage 36 integrally mounted on the holder base upper        surface 32 a with its one end and having at its other end a        gemstone supporting surface 37 configured for contacting the        resting surface S (best seen in FIG. 4) of the gemstone when        mounted thereon and defining an illumination plane IP (best seen        in FIG. 2B) parallel to the XY plane of the RCCS of the system        10. With reference to FIG. 2A, The X-Y plane of the RCCS        separates the space within the cavity 15 into a gemstone space        15 a disposed above, and a stage space 15 b disposed below, the        plane of the gemstone supporting surface, with respect to        vertical, gravity direction.

It should, however, be noted that such vertical orientation of the towerstage and the gemstone is not the only one possible. Any otherappropriate orientation can be used with corresponding specialarrangement for holding gemstones, as known in the art.

Reverting now to FIGS. 1A and 1B, the holder base lower surface 32 b isconfigured for detachable fitting thereof to the holder mounting surface42 a of the stage base 42 so as to lock the holder 31 to the stage base42 in a position that the tower stage of the holder is coaxial with theaxis of rotation RA and the axis Z of the system 10.

The gemstone holder 31 is selected from a set of holders 31 a to 31 ncorresponding to several gemstone size groups A to N to be modeled withthe system 10. FIG. 3 schematically illustrates three such gemstoneholders 31 a, 31 b, 31 c corresponding to three gemstone size groups A,B, C. Each size group is defined by a range of carat weights for whichthe corresponding holder size is suitable. Gemstones 1 _(A), 1 _(B), 1_(C) in FIG. 3 each respectively represents a stone from one of therespective size groups A, B, C.

The main difference between the different holders 31 a to 31 n is in thegemstone support height SH, at which the gemstone supporting surface 37is located relative to the holder base lower surface 32 b, and which indifferent holders is, respectively, SHa to SHn so as to ensure that thelarger the size of a gemstone, the lower it is mounted relative to theholder base, i.e. the shorter the height SH. In other words, among theholders 31 a to 31 n, the holder with a maximal height SHmax isconfigured to support the smallest gemstones which the system 10 isconfigured to model. With the thickness of the holder base 32 (i.e. thedistance between its upper and lower surfaces 32 a and 32 b) being BH,the height of the tower stage 36 (i.e. the distance between the gemstonesupporting surface 37 and the upper surface of the holder base 32) beingTH, and the gemstone total support height being SH=TH+BH, the differencebetween different gemstone support heights SHa to SHn of differentgemstone holders is obtained in the described example by providing thecorresponding different heights BHa to BHn of the gemstone holders 32,and keeping constant the height TH of the tower stage 36.

In addition, the gemstone holders 31 a to 31 n differ in the area oftheir gemstone supporting surfaces 37, which is greater for the groupsof gemstones which have greater sizes, and which is such as to ensurethat any surface of the gemstone that is adjacent to its resting surfaceS but is other than the resting surface, protrudes radially from thegemstone supporting surface 37 when the gemstone is mounted thereon.Exemplary, each of the gemstones shown in FIGS. 3 and 4, is so mountedon the gemstone supporting surface 37 of the tower stage 36 that itsresting surface S is constituted by a central portion of its table GTwhilst the periphery of the table GTP and edges GTC of its intersectionwith the gemstone's crown C protrude radially from the gemstonesupporting surface 37.

It needs to be noted that, while the above described configuration withseveral holders 31 n is one option for achieving the goal of placing thegemstone in the necessary position for analysis, other appropriatearrangements can be used. For example, instead of a plurality of holders31 n, there can be configured a tower stage 36 which is displaceablymounted within stage base 42, such that it can displace a gemstone alongthe Z-axis, and its support surface 37 can be either constant indiameter, or can be adjustable in its diameter.

As seen, in the present example the gemstone's resting surface is itstable. However it should be understood that such orientation of thegemstone is not obligatory and it can be mounted in the system in anyother appropriate orientation. In addition, it should be understood thatthe orientation of the entire stage station or of its selectedcomponents including the gemstone supporting surface 37 can be otherthan that shown in the drawings.

The system 10 can further comprise a displaceable centering mechanism50, having a centering axis, which is configured for being:

-   -   placed in its operative, centering position in which it can        receive therein and center, on the gemstone supporting surface        37, the gemstone G so that the centering axis of the centering        device coincides with the rotation axis RA and axis Z of the        system 10, and    -   subsequently displaced from its centering position to take its        inoperative position at a location spaced from the gemstone        supporting surface 37 and from the space between holder base 32        and the gemstone supporting surface 37.

The First 3D Modeling System 60

The first 3D modeling system 60 can be of any known type configured forthe conventional computer calculation of a 3D model of the gemstone G,and it can be, for example, DiaMension™ system produced by SarinTechnologies Ltd., Israel, to which the description below particularlyrefers.

As shown in FIGS. 1A and 2A, the system 60 includes a backlightillumination unit 62 and an imaging device 70 aligned along the firstoptical axis FOA, both mounted on the system base 12 on opposite sidesrelative to the gemstone supporting surface 37, so as to enable theimaging system 70 to scan the outer surface of the gemstone G whenmounted on the gemstone mounting surface 37 and rotated by the stagebase 42, and obtain thereby a plurality of electronic images of thesilhouettes of the gemstone surface in different angular positions ofthe gemstone relative to the axis Z, and to transfer the obtainedelectronic images via direct line 222 to the computer system 300configured to calculate the original 3D model of the gemstone.

The computer system 300 can be implemented as a separate systemcomponent operatively connected to other system components or can be, atleast partly, distributed over some or all of the system components. Thedetailed below functions of the computer system 300 can be implementedin any appropriate combination of software, firmware and hardware.

The optical axis FOA of the first modeling system 60 intersects the axisZ at the XY plane, spaced along the Z axis from the holder supportingsurface 42 a of the stage base 42, to a constant distance, which exceedsthe maximal support height SHmax. Due to this and due to the use of thegemstone holders 31 a to 31 n, which provide gemstones of differentsizes with different support heights SHa to SHn, it is ensured that anygemstone among those for the modeling of which the system 10 isdesigned, disposed on the gemstone supporting surface 37, will be fullyin the field of view FOV60 of the imaging system 70 during itsoperation.

The Second 3D Modeling System 100

Reverting to FIG. 1A, the second 3D modeling system 100 comprises asecond illumination system generally designated as 110, and a secondimaging device 200 configured for obtaining images of small areas on thepavilion, crown or girdle of the gemstone G, with at least one of amagnification and resolution being higher, and/or depth of focus beinglower, than those provided by the first imaging device 70. Examples ofsuch areas are shown in FIG. 4, illustrating a gemstone G mounted on atower stage 36, supported by the gemstone supporting surface 37 alongits resting surface S. The areas shown in FIG. 4 are areas P1 and P2 ofthe pavilion P of the gemstone, C1 and C2 of the crown of the gemstone,and G1 and G2 of the girdle GI of the gemstone.

As seen in FIG. 1A, the second illumination system comprises a pluralityof illumination sources 120, 160 and 190′ differently disposed relativeto the second imaging device 200, which disposition is such as to allowthe illumination sources to direct their illumination to a space withinthe cavity 15 of the system 10, between the rotation axis RA and aproximal end 200′ of the second imaging device 200 in order toilluminate at least areas of the pavilion, crown and girdle of thegemstone G, which are closest to the second imaging device 200.

With reference to FIGS. 2B to 2E (illustrating different parts of thesystem 10 without the gemstone G), the second illumination system 110thus comprises:

-   -   a) a pavilion illumination device 120 best illustrated in FIG.        2B, disposed in the gemstone space 15 a of the system cavity 15        above the gemstone supporting surface 37 so as to illuminate at        least a portion 121 of space between the rotation axis RA and        the proximal end 200′ of the second imaging system 200, adjacent        to the gemstone supporting surface 37.    -   b) a crown illumination device 160 best seen in FIGS. 1B and 2C,        in the form of a light guiding body having a light exit surface        161, movable between an inoperative position thereof (not        shown), in which it is spaced from the system cavity 15, and an        operative position, in which the light exit surface 161 is        disposed in the stage space 15 b of the system cavity 15 below        the gemstone supporting surface 37, so as to illuminate at least        a portion 121 of space between the gemstone supporting surface        37 and the proximal end 200′ of the second imaging system 200,        adjacent to the gemstone supporting surface 37; in particular,        when moving from its inoperative to its operative position, the        light exit surface 161 of the crown illumination device is at        least partially brought into a region 123 between the gemstone        holder base 32 and the gemstone supporting surface 37, thereby        ensuring that the light exit surface 161 is disposed at a        constant distance D from the gemstone supporting surface 37        irrespective of the size of holder 31 or the gemstone.    -   c) A girdle illumination device, two different examples of which        are shown in FIGS. 2D and 2E; the girdle illumination device        190′ shown in FIG. 2D is disposed adjacent the proximal end 200′        of the second imaging device 200 at a constant spacial        relationship with the proximal end 200′, so as to traverse at        least a portion of the space 121 between the rotation axis RA        and the proximal end 200′ of the second imaging system 200, and        illuminate the gemstone space 15 a above and adjacent to the        gemstone supporting surface 37, potentially from both the stage        space 15 b and the gemstone space 15 a; the girdle illumination        device 190″ shown in FIG. 2E is disposed on the side of the        gemstone supporting surface 37 opposite the proximal end 200′ of        the second imaging device 200, so as to illuminate at least the        gemstone space 15 a above and adjacent the gemstone supporting        surface 37.

The girdle illumination device can be configured to provide illuminationof any appropriate type, such as for example, diffused illumination.

In order to increase contrast between adjacent facets of the pavilionand/or crown when imaged by the second imaging device 200, any one ofthe pavilion and crown illumination devices can be configured to producea uniformly diffusive light beam, and can be so spaced from the gemstonesupporting surface 37 along the rotation axis RA, so as to provide arespective predetermined opening angle α_(p), α_(c) of its light whenincident on the illumination plane IP coincident with the supportsurface 37.

Referring now to FIG. 4 specifically, the opening angle α_(p), α_(c) isdetermined in correspondence with angles σ_(i) formed by normals N_(i)to facets that are adjacent to each other, which facets are expected tobe in the field of view P1 of the second imaging device 200, withrespect to each other (see FIG. 4, N₁ and N₂; σ₁) and to the pavilion orcrown illumination axis PIA or CIA (see FIG. 4, ω_(p) for example),respectively. All these angles are known from the planned cut geometryof the gemstone and, thus, the value of the opening angle can beobtained empirically for stones of the same or similar planned cutgeometry. There can thus be provided a table presenting differentpositions of the pavilion/crown illumination device per planned cutgeometry, and adjustment of such position can be performed manually bythe user or automatically.

Reverting to FIG. 2B, a pavilion illumination axis PIA is defined by thecentral normal of a light exit surface 122 of the device 120, forming anacute angle y with the rotation axis RA and intersecting the opticalaxis SOA at a location IL within the space 121 between the gemstonesupporting surface 37 and the proximal end 200′ of the second imagingdevice 200. A crown illumination axis CIA, which is normal to the lightexiting surface 161, intersects the axis SOA at a location between thetower stage 36 and the distal end 200′ of the second imaging device 200.

In one specific example, the pavilion illumination device 120 cancomprises a plurality of LEDs at one end thereof, with respective lensesand diffuser elements causing the light to exit from the device 120 asdescribed hereinabove in a diffused light beam.

In addition, the pavilion illumination device 120 can be provided with acontrast enhancing mask 140 disposed adjacent its light exit surface122, directed to provide a non-uniform illumination pattern in the space121, and thereby increase a contrast between adjacent facets. By way ofnon-limiting examples, such mask can have at least one of the following:

-   -   i. areas exhibiting distinct absorption properties;    -   ii. differently polarizing areas;    -   iii. areas providing different light propagation properties.

The number of areas in the above pattern can correspond to the number offacets expected to be in the field of vision of the imaging device 200.

One example of the mask 140 designed in accordance with option (i) aboveis shown in FIG. 5, in which segments 140 a and 140 b are configured tofully absorb, and segments 140 c and 140 d are configured to fullytransmit, light exiting from the pavilion illumination source 140.

In the described system, by way of non-limiting example only, the crownillumination device is in the form of a light guide 170 with a proximalend 175 configured for receiving a light source, such as a LED 174, sothat it emits light within the light guide, a distal end 177 configuredfor emitting light reaching the distal end toward the portion 121 of thespace located between the gemstone supporting surface 37 and theproximal end 200′ of the second imaging system 200, and an intermediateportion 176 therebetween via which the light emitted from the lightsource propagates by multiple reflection thereof from the light guidesurfaces 172, which can be provided with a reflective coating. Thedistal end 177 of the light guide can be provided with means, such as adiffusive coating or plate 161 configured to uniformly diffuse lightexiting therefrom.

The crown illumination device can also be enhanced by masking the lightexit surface 161 according to the same principles and details describedabove for the pavilion illumination device 120.

It is furthermore clear to the skilled person, that the above describedlight guide of the crown illumination device 160 is only one specific,non-binding example of numerous strategies for illuminating a gemstonemounted on stage 31 from below.

There are many other ways of achieving the same goal, for example,amongst others, by placing an OLED at the location of light exitingsurface 161, or concentrating the light of more than one LED by a singlelight guide of a different form, or using fiber optics, only to namethree more examples.

If desired, the illumination devices can be provided with degrees offreedom required to obtain their desired position and effect. As shownin FIG. 1A, in the described example, the degrees of freedom for thepavilion illumination device 120 can be provided by the possibility ofmoving the same in at least one of the following manners: translationalong a first axis K1 parallel to the Z-direction, rotation about asecond axis K2 that is perpendicular to a plane passing through the Zaxis and the second optical axis SOA, and translation along a third axisK3 parallel to axis Y.

The computer system 300 can control respective devices of the system viacontrol card 310. In the described example, this concerns all devicesexcept for the electronic imaging devices, as described further andhereinabove, which in the described example is connected to the computersystem 300 by direct communication lines 222. However, this does notneed to be the case and should be seen as optional.

The second imaging system 200 will now be described in more detail, withreference to FIG. 1 a.

The second imaging device 200 comprises an optical system 220 and anelectronic imaging device 240 (not seen), both mounted within a housing226, and a mechanical positioning arrangement 270 for supporting thehousing 226 and moving it as required.

The optical system 220 can be a telecentric optical system providing thesame magnification X at all distances therefrom. Optionally, there canbe mounted an iris or other device for adjusting the depth of focus andthe resolution of the system, either manually or automated.

The second imaging device 200 is configured to provide images formed bythe optical system 220 and recorded by the electronic imaging device240, with depth of focus and a resolution optimized to distinguish edgesof a gemstone along a distance L which is not shorter than the length ofthe smallest planned edge of the smallest stone to be measured by thesystem and, optionally, not greater than a fraction of the maximaldimension of such smallest stone. The optimization of depth of focus andresolution, with the resultant magnification, is aimed at attainingimages of small areas of the gemstone, such as for example, the areas ofjunctions of the gemstone including only parts of the associated facetsthat are adjacent thereto, with a quality sufficient for distinguishingdetails of said areas such as intersections between the imaged facets'parts, along the required distance, and it will ultimately result inthat at least one of the magnification and resolution being higher,and/or depth of focus being lower, than that provided by the firstimaging system when obtaining the original 3-D model.

The second imaging system 200 can further comprise image enhancingdevices in the form of filters or polarizers 201 placed in front of theoptical system 220, and thereby contrast of the images can be enhanced,or normally invisible structural effects can be made visible, if needed,thereby further enhancing the abilities of the system to accuratelydistinguish particulars needed for describing the gemstone.

The electronic imaging device 240 is in the form of a CCD camera whichreceives on its sensing pixels a magnified image formed by the opticalsystem 220 and produces electronic images to be communicated via directline 222 to the computer system 300.

The positioning arrangement 270 is configured to support the housing 226with the optical system 220 and the electronic imaging device 240, andto provide translation thereof along an axis I₁ parallel to and spacedfrom rotation axis RA along a direction parallel or coinciding with thesecond optical axis SOA, as well as translation along the second opticalaxis SOA, and optionally to provide for rotational displacement aroundan axis I₂ perpendicular to the rotation axis RA and the SOA, as well asa translation along axis I₂. To this end, the positional arrangement 270is connected to suitable step motors (not shown) that are controlled viacontrol card 310 and communication line 223 by the computer system 300.

The computer system 300 is configured to control the operation of thestage station and the illumination and imaging systems, to execute imageprocessing analyses and 3D computations necessary for performingcorresponding computational steps described hereinbelow, and to providea graphic user interface for human/machine interaction for controllingthe whole 3D modeling process, and capable of presenting 3D models tothe user.

In operation, the stage 30 rotates the mounted gemstone 1 such as tobring its side at which a surface portion to be imaged is disposed infront of the second imaging system 200; the mechanical positioningarrangement 270 moves the second imaging system 200, as required tobring the surface portion to be imaged into the field of view FOV of thesecond imaging system and at such distance from the second imagingsystem as to ensure that the optical system 220 is focused on thesurface portion to be imaged.

The system 10 can further comprise a cover (not shown) to cover thecavity 15 thereof from outside influence at least during operation ofthe system.

The above system 10 can be built as a completely new system or can beproduced as an upgrade of an existing system configured for producing aconventional 3D model of a gemstone, which includes a conventional stageand a conventional 3D modeling system.

With reference to FIGS. 7A to 7D, the following are the steps that canbe performed in accordance with one example of such upgrading of anexisting 3D modeling system 620, which can be Sarin's DiaMension™, withan existing stage 610, existing stage base 611, existing machine base612, motor 615, computer system 300 configured in an existing manner,and existing control card 628:

-   -   the existing stage 610 with its existing stage base 611 is        disassembled in its entirety from the existing machine base 612;    -   the motor 615 mounted in the existing system at position M1, at        height MH1 from the Y-axis, is re-mounted at a lower position,        at height MH2;    -   a new stage, which is built according to all the features and        functionalities as described hereinabove for stage 30, is        mounted in the same location instead of the existing stage 610,        with the main difference that the stage base 42 is laid lower        than the existing stage base 611 of the stage 610 by a height A;    -   referring now to FIG. 7B, an illumination system 710, with all        features and details according to the illumination system 110,        and an imaging device 720 with all features and details        according to the imaging device 200, are installed in the        corresponding locations as described above, to form the second        3D modeling system;    -   a new driver card 750 for the system is supplied and connected;        and    -   the computer system 300 is provided with a capability for        controlling the system and providing necessary computations as        described below.

Finally, a new cover is mounted to reversibly cover the mounting cavitywith all its illumination devices 15 from outside influence at leastduring operation of the system.

Operation of the System 10

Whether built as a completely new system or as an upgrade of an existingsystem, the operation of the system 10 for producing an accurate 3Dmodel of the gemstone G can comprise all or a part of the stepsdescribed below, with reference to block-diagrams 5A to 5C, depending ondesired scope of examination of a gemstone.

Stage I: Gemstone Mounting and System Preparation

In step 1000, a size group (for example group B) for a gemstone 1 (forexample gemstone 1 b) to be examined is chosen among the groups ofgemstones with which the system 10 is planned to operate (see FIG. 3 andcorresponding explanations above).

Step 1001, it is ensured that the gemstone holder 31 of a correspondingsize (in this case the gemstone holder 31 b) is mounted on the stagebase 42 and a lens is mounted in the imaging device 70 selectedaccording the size group of the stone. During mounting of the gemstoneholder 31, if required, the crown illumination device 160 is in itsinoperative position, after which it is brought back to its operativeposition.

In step 1002, the stone is thoroughly cleaned and mounted on thegemstone holder 31, which in turn is mounted on the stage base 42, asdescribed in detail hereinabove.

In step 1003, if a centering mechanism is used, it is utilized now, andthen removed from the stage so as not to interfere with the operation.

If the system allows adjustment of the position of any of the pavilion,crown and girdle illumination devices by a user, this should be done ina next step (not included in FIG. 5A).

Upon activation of the system 10 by means of the respective command inthe GUI 350, the system operates automatically as described below undercontrol of the computer system 300.

Stage II: Scanning the Gemstone by the First 3D Modeling System 60 toProvide an Original 3D Model Thereof

In step 1004, the first 3D-modeling system 60 is activated, the stagebase 42 with the gemstone holder 31 and the gemstone is caused to rotateby predetermined amounts, the backlight illumination unit 62 illuminatesthe gemstone, and for each incremental rotation, an image of thesilhouette of the gemstone against the bright backlight is formed andrecorded by the first imaging device 70, until the gemstone has beenrotated 360 degrees (alternatively the rotation of 180 degrees can beused where this is sufficient to obtain all necessary silhouettes of thestone).

In step 1005, upon completion of the process of obtaining silhouetteimages, the computer system 300 extracts 3D-relative coordinates of theimaged gemstone from the images by edge recognition techniques, andcalculates the original 3D model 400 based on the extracted data, whichincludes inter alia a plurality N of revealed junctions and edges.

Stage III: Obtaining a More Accurate 3D Model of the Gemstone by theSecond 3D Modeling System 100

Sub-Stage III.1: Distinguishing Edges and Junctions

Without moving the stone relative to the supporting surface 37, in thenext step 1006, the second 3D modeling system 100 chooses a selectedjunction N1 amongst the revealed junctions found by the computer system300.

In step 1007, the computer system 300 provides instructions to activateat least one of the three illumination devices, according to thelocation of the selected junction N1: if the selected junction N1 islocated on the pavilion, the pavilion illumination system 120 isactivated, if the junction N1 is located on the crown, the crownillumination system 160 is activated. At any time during operation, atleast one, suitable illumination device is active. Sometimes it can beadvantageous to operate two illumination devices; for example bothpavilion and crown illumination devices can be used when junctions atthe merger of the crown and table of the stone need to be imaged.

The system in step 1008 rotates the gemstone holder 31 and moves theimaging system 200 by means of the above described features to bring theselected junction N1 within the field of view FOV of the imaging systemand to focus the imaging system on the junction N1.

In step 1009 an i number of images of the junction N1 is taken, underdifferent lighting conditions LN1, with i>1. The lighting conditions LN1are produced by a slight rotation of the gemstone 1 b relative to thesecond 3D modeling system per increment, such that the selected junctionN1 remains in the FOV of the imaging system, but under changed angles ofits facets relative to the respectively operative illumination systemand imaging system, thereby changing the light pattern reflected by thefacets of gemstone 1 b towards the imaging system 200, and producingdifferent contrasts between the facets.

In step 1010, the computer system 300 compares the i images of thejunction N1, and selects the best image with contrasts best suited forfurther processing (in the steps 1011-1025 below)

Referring now in particular to FIG. 6E, in step 1011, the computersystem 300 determines particulars such as all detectable edges DE basedon the selected image and establishes their coordinates:

-   -   For facets F1 and F2, the computer system 300 distinguishes a        difference D12 in pixel color or brightness value at their        mutual border MB12. The location where this difference D12 is        largest is then defined as detected edge DE12.    -   Likewise, based on all facets F1 to F4, all other detected edges        DE23, DE34, DE14 and DE24 are defined, and their coordinates are        recorded, for further processing;    -   If in step 1011 no edges are visible, then step 1011 a is        performed.

If in step 1011 edges are visible, then step 1012 is performed.

In step 1012, the computer system 300 determines discrepancies betweenthe number of edges NE detected in the selected image and the number ofedges NER revealed in the junction N1 of the original 3D model. IfNE>NER, there are new edges present in the selected image, and this isthus recorded in a list of images with new edges for later processing.

If NE<NER, there are edges missing in the image, and subsequently, step1011 a is performed.

In step 1011 a, the computer system 300 associates all edges in theselected image with edges present in the original 3D model. Thus, if thenumber of revealed edges in the original 3D model at the regioncorresponding to that shown in the selected image, is greater than thenumber of edges found in the image, the superfluous edges present in theoriginal 3D model, but missing from the image, are subtracted, andeventual adjacent facets are merged.

In step 1013, the computer system stores results of the previous stepsin its memory or in another suitable non-transitory computer readablemedium.

In step 1014, the computer system 300 checks for the revealed junctionsthat have not yet been processed. If there are such junctions left, thecomputer system moves to the next junction in its list, and jumps backto step 1007.

This loop is executed, until there are no revealed junctions left.

Once all the revealed junctions have been examined, and referring now toFIG. 5B, in step 1014 a, the computer system compares the number ofjunctions NJ in the planned geometry to the number of revealed junctionsNJR in the original 3D model, and if NJ>NJR, again, there arenon-revealed junctions. The computer system records coordinates of thesenon-revealed junctions in a list for non-revealed junctions NoJR.

In step 1015 the computer system chooses between the two lists NER andNoJR as follows:

-   -   the system checks first, if the list NER contains items, and if        in the affirmative, it chooses this list and enters sub-stage        III.2. If the list NER is empty, the system then moves to the        list NoJR, and enters sub-stage III.3. If the list NoJR is        empty, the system moves to step 1110 and starts sub-stage III.4,        the girdle analysis, if a girdle is to be found.

If no girdle is to be found, the computer system moves to step 1200, andbuilds

Sub-Stage III.2: Determining New Junctions Based on New Edges

In step 1017, the computer system has determined new edges byassociating each edge in the image with a revealed edge in the original3D model. Since, for all images in this list NER, by definition thereare more edges than revealed edges, at the end of this process there arenew edges disclosed. The computer system records all new edges of everyselected image with their coordinates.

Since the coordinates of all new edges of every selected image have beenrecorded, the coordinates of their projections away from the junctionfound in the image can now be calculated and a potential junction areais determined where this extension is expected to meet with a respectiverevealed edge of the original 3D model. The coordinates for hispotential junction area are recorded by the computer system.

The manner in which new edges and new junctions are associated to theoriginal 3D model is described at the end of this description, in moredetail with reference to FIGS. 6A to 6D.

For each potential junction area, step 1018 is performed by the computersystem 300, by listing the potential junction as a revealed junction,and the respective image is removed from the list NER; as long as thereare still items in the list NER, the computer system then jumps back tostep 1017.

If there are no new items in the list NER, i.e. NER is empty, thecomputer system performs step 1020 by jumping back to step 1007 andperforming the sub-stage III.1 of steps 1007 to 1014, with eachpotential junction area now recorded as revealed junction.

Upon reaching step 1015, with an empty list of NER, the computer systemwill now either find items in the list NJR and process with thesub-stage III.3 described below, or it will find both lists empty.

Sub-Stage III.3: Determining New Junctions Based on the Planned Geometry

If there are items in NoJR, the computer system performs step 1122 bynumbering the non-revealed junctions, and the computer system chooses apotential new junction NoJ1.

In step 1123, the computer system provides instructions for focusing theimaging system on the location for the potential new junction NoJ1.

In step 1124, if a new junction is found, the location is recorded asrevealed junction. If no junction is to be found, the computer systemperforms step 1011 a and follows the subsequent routine back to step1015, where it will again find items in the list NoJR, and continue inthe routine of steps 1122-1124.

If a new junction is found, the computer system performs step 1125 bydeciding if this was the last potential new junction. If not, thecomputer system jumps to step 1123. If in the affirmative, the computersystem performs step 1126 and returns to sub-stage III.1, steps1007-1014, and again repeats this loop until there are no revealedjunctions left in the list.

In step 1026, the computer system decides whether to progress to step1110 (FIG. 5C)—to the girdle analysis process—or to forego girdleanalysis and progress to step 1200. This decision can be made based onhuman intervention or automatically upon finding of a girdle.

Stage IV: Building an Accurate 3D Model

In step 1200, the computer system builds an accurate 3D model of thegemstone based on all saved results.

Optional Sub-Stage III.4: Girdle Analysis

In step 1026, the computer system progresses to step 1110 (FIG. 5B)—tothe girdle analysis process.

In step 1110, the computer system provides instructions for girdleillumination activation, and for shutting-off all other illuminations.

In step 1111, the girdle is scanned by capturing a plurality of imagesof different sections thereof. This scanning process is performed suchthat the whole girdle is imaged by the respective imaging system.

In step 1112, the images are analyzed by the computer system 300, andall distinguishable particulars are recorded. These particulars are usedby the computer system in step 1113 to determine new girdle featuresabsent from the planned girdle geometry, such as for example extrafacets and/naturals.

The computer system thus first identifies the region where a new girdlefeature is located, which can be at a location adjacent the place, wherea junction is missing that was supposed exist, according to the plannedpavilion/crown geometry, or where in the images taken in step 1111,there is a distortion in the girdle pattern relative to the one planned.

The computer system then defines borderlines of the above region, itsshape and area and the new girdle feature is classified. For example, ifthe borderlines are straight lines, the new girdle feature is an extrafacet, which is a planar surface. If the borderlines are not straightand clearly defined, this would be typical of a natural. Thus, in step1114 the computing system makes a decision on the manner, in which eachnew girdle feature is to be represented in the accurate 3D model, andthe corresponding information is stored.

Stage IV′: Building an Accurate 3D Model with Girdle Information

In case the sub-stage III.4 is performed, in step 1200 described above,the accurate 3D model of the gemstone can be complemented with girdleinformation obtained therein, based on images of differentsections/particulars of the girdle and/or there description. Thisinformation can be in the form of the graphical representation of newgirdle features, such as extra facets and/or naturals, added at thecorresponding position on the girdle in the accurate 3D model of thestone, e.g. by drawing and presenting by the computer system borderlinesof the new feature, and even adding thereto its graphical representationof its appearance as it appears in a corresponding image. The computersystem can also knit the images of different sections of the girdletogether to form a developed view of the whole girdle.

Associating, by the computer system. new edges and new junctions to theoriginal 3D model, referred to in sub-stage III.2 described above, willnow be described with reference to FIG. 6A-6D, illustrating the way inwhich the computer system, based on the data described hereinabove,associates new edges and new junctions to the 3D model.

In a first case, where only a facet is missing but two revealedjunctions PA1 a, PA1 b connected by the edge exist and are known, thecomputer system, upon examining junction PA1 a, will detect that the newedge NE is supposed to connect to a second revealed junction PA1 b andwill verify at this second revealed junction PA1 b if there is a missingedge NE′ there, too, to verify the missing facet. If it didn't detectthe missing edge at the second revealed junction PA1 b, it will needanother set of images along the detected edge to detect where this edgeis connected to.

In a second case, where there is a missing junction, this means that afacet is missing and also the junction PA3 where the edge supposed toconnect to is unknown. The computer system will calculate where theprojection PNE2 of edge NE2, originating at the revealed junction PA2 issupposed to be connected to, and it will find that there is no knownjunction in that direction. The edge will then join with anotherrevealed edge RE and that will be a suspicious position for the missingjunction PA3. The computer system will need another set of images ofthis suspicious area at the suspicious position PA3 to verify if thepartial edge NE2′, which is the end point of the projection from NE2, isreally forming a junction there.

It should be noted that though in the above exemplary description ofoperation of the system, the analysis of the gemstone is performed forall its non-planar parts, namely, pavilion, crown and girdle, this doesnot necessarily need to be the case. Depending on the purpose of theanalysis, only one part of a gemstone can be accurately modeled, e.g.when only one part of a rough stone has been cut to have a planned cutgeometry.

Moreover, a system according to presently disclosed subject matter canbe used for obtaining images of a gemstone for any desired purpose, withor without focusing on any particular locations and analyzing imagesthereof to find features not revealed by the method described above.

1-50. (canceled)
 51. A method for producing a 3D-Model of an externalsurface of a gemstone, said method comprising: a) taking a plurality ofimages of the gemstone and using the plurality of images for generatingan original 3D-model of an external surface of said gemstone includingfacets, edges abounding said facets, and junctions each constituting anarea of meeting of at least three said edges associated with at leasttwo facets; b) using the original 3D model generated in step a) toobtain information, based on which location of one or more selectedjunctions is determined, and subsequently imaging an area of each suchselected junction with only portions of associated facets thereof andedges disposed adjacent said selected junction, said imaging beingperformed under illumination conditions different from those, at whichsaid plurality of images were taken and providing such contrast betweenadjacent facets as to allow to distinguish an edge therebetween; c)analyzing results of said imaging to obtain information regarding thearea imaged in step b); and d) using the information obtained in step c)for producing an improved 3D-model of said external surface of thegemstone, which is more accurate than the original 3-D model.
 52. Themethod according to claim 51, wherein the gemstone has a planned cutgeometry and wherein the original 3D-model of the external surface ofsaid gemstone comprises revealed edges and revealed junctions, and step(a) further includes selecting said at least one selected junction in atleast one of the following manners: e) considering at least one of therevealed junctions to be said selected junction; or f) determining atleast one non-revealed junction existing in said planned cut geometrybut absent from said original 3D model, considering a predicted locationof said non-revealed junction to be said selected junction.
 53. Themethod according to claim 51, wherein said gemstone is a cut gemstonehaving a girdle with planned girdle features, which are features thatthe girdle was planned to have when it was cut, the method furthercomprising the following steps: g) obtaining one or more images of atleast one selected portion of said girdle, said one or more images beingtaken under such conditions as to enable distinguishing at least one ofsaid planned features at said selected portion of the girdle; h)analyzing said one or more images to obtain information regarding thegirdle at said selected portion thereof; and i) using said informationwhen producing said improved 3D-model in step (d).
 54. The methodaccording to claim 51, further comprising predicting a new junctionabsent from the original 3D model and from the planned cut geometry,based on the information obtained in step (c), considering said newjunction to be a selected junction and performing said steps (b) to (d)with respect thereto.
 55. The method according to claim 54, wherein whena new edge is determined which is absent from the original 3D model,said predicting is performed by associating said new junction with apredicted end of the new edge at its predicted intersection with an edgerevealed in said original 3D model.
 56. The method according to claim51, wherein when based on the information obtained in step (c), it isrealized that at least one revealed edge is missing from any image ofits associated junction, such missing edge is not included in theimproved model in said step (d).
 57. The method according to claim 51,wherein the imaging in step (b) is performed under an imaging conditionconstituted by at least one of the magnification and resolution, whichis higher than that at which the original 3-D model was obtained. 58.The method according to claim 51, wherein the imaging in step (b) isperformed under an imaging condition constituted by a depth of focus,which is lower than that at which the original 3-D model was obtained.59. The method according to claim 51, wherein said gemstone is supportedby a gemstone stage station including a gemstone holder with a gemstonesupporting surface, and a stage with a holder mounting surface whosecenter has a disposition which is invariant relative to a first opticalaxis FOA of an imaging device used in step (a) for gemstones of any sizewhich the system is configured to examine, and the distance from whichto the gemstone supporting surface is variable depending on the size ofthe gemstone, so that in a relative Cartesian coordinate system (RCCS)said first optical axis FOA is defined by the Y—axis of the RCCS andsaid distance is variable along the Z axis, which optionally constitutesan axis of rotation of the gemstone holder relative to said imagingdevice and/or to an imaging device used in step (b).
 60. The methodaccording to claim 51, wherein said gemstone is illuminated in step (b)with such an illumination that at least three adjacent facets of thecrown or the pavilion, or two facets of the crown or the pavilion andthe girdle, are each at least partially illuminated with such a contrastbetween at least one couple of their adjacent illuminated surfaces as toenable distinguishing an edge therebetween.
 61. The method according toclaim 59, wherein the gemstone has a resting surface in contact withsaid gemstone supporting surface, and said supporting surface has suchdimensions as to allow adjacent portion of the gemstone to radiallyproject therefrom, and wherein optionally, the resting surface of thegemstone is at least the majority of its table, and the projectingportion is at least its crown and, possibly, an area of the tableadjacent thereto.
 62. The method according to claim 51, wherein saidstep (b) comprises obtaining a plurality of images of the or eachselected junction and selecting thereamongst at least one selectedimage, in which one or more edges seen therein are distinguished betterthan in other images.
 63. A system for automatically producing a3D-Model of a gemstone, the system comprising: a 3D modeling systemconfigured for taking a plurality of images of the gemstone and usingthem for generating an original 3D model of an external surface of agemstone, including facets, edges abounding said facets, and junctionseach constituting an area of meeting of at least three said edgesassociated with at least two facets; an illumination and imaging systemconfigured for imaging an area of each junction selected from one ormore junctions, whose location is determined using the original 3Dmodel, said area including in addition to said junction only portions ofits associated facets and edges disposed adjacent the junction, saidillumination and imaging system being configured to perform said imagingafter said plurality of images have been taken and said original 3Dmodel has been generated, said imaging being performed underillumination conditions that are different from those, at which saidplurality of images were taken, and that provide such contrast betweenadjacent facets as to allow to distinguish an edge therebetween; and acomputing system configured to operate the system, in accordance withthe method of claim 1, for automatically producing an improved 3D model,which is more accurate than the original 3-D model.
 64. The systemaccording to claim 63, further comprising a stage station with a holderand holder mounting surface; a step-(a) illumination and imaging devicesfor performing the step (a) of said method, said devices constituting apart of said 3D modeling system and having a first optical axis FOAcongruent with the Y axis of a relative Cartesian coordinate system(RCCS), the X-Y plane separating between a gemstone side and a stageside of the system along the Z axis; and step-(b) illumination andimaging devices, each constituting a part of said illumination andimaging system, for performing the step-(b) of said method, wherein atleast one of the step (b) illumination devices is different from that ofstep (a).
 65. The system according to claim 64, wherein the step-(b)illumination devices comprise at least two step-(b) illumination devicesconfigured to provide illumination in the form of a diffusedillumination beam of an opening angle α, propagating in a propagationdirection along its chief ray, each one of said at least two step-(b)illumination devices meeting one of the following conditions differentfrom that met by at least one other of said step-(b) illuminationdevices: s) it is disposed on the gemstone side of the system, is spacedfrom the X-Y plane to a variable distance along Z axis, so that thechief ray of said diffused illumination beam forms an acute angle withsaid Z direction; t) it is disposed on the stage side of the system, isspaced from the X-Y plane to a constant distance along Z axis, so as toilluminate mainly an area disposed between the Z—axis and said step-(b)imaging device; and u) it is spaced radially from the Z axis on thestage side or gemstone side of the system, its propagation direction hasat least a vector component perpendicular to the Z—axis, and the spatialrelationship between the device and said step-(b) imaging system isconstant.
 66. The system according to claim 64, wherein the holder isselected from a set of at least two holders of different dimensionsconfigured to support gemstones from at least two size groups by way ofa support surface such that the distance between each respective supportsurface and the holder mounting surface of the stage station is suchthat the respective gemstone of each size group is placed within thefield of vision of said step-(a) imaging device, and optionally thesupport surface coincides with said Y-axis.
 67. The system according toclaim 64, wherein the step-(b) imaging device is configured for takingimages with at least one of a magnification, resolution or depth offocus, being different than that provided by the step-(a) imagingdevice.
 68. The system according to claim 64, wherein the step-(b)imaging device is configured for taking images with at least one of thefollowing: a magnification higher than that provided by the step-(a)imaging device; a resolution higher than that provided by the step-(a)imaging device; and a depth of focus lower than that provided by thestep-(a) imaging device.
 69. The system according to claim 63, whereinthe computing system comprises a processor with a capability for imageanalysis allowing it to choose out of a plurality of images at least oneselected image, in which one or more edges are distinguished better thanin other images.
 70. The system according to 64, wherein said computingsystem is further configured for operating the system after a gemstonehas been mounted on said gemstone supporting surface, as follows: bb)causing said step-(b) imaging device to record a plurality of images ofsaid selected surface portion of the gemstone at a correspondingplurality of relative positions of said stage and said step-(b)illumination devices, said images differing in the illuminationconditions for distinguishing of said detail, cc) comparing said images,deciding if at least one of the images offers said conditions fordistinguishing said detail, and vi) if in the affirmative, selectingsaid one of the images a selected image; and vii) if in the negative,repeating said steps (bb), (cc) until at least one image is selected asbeing said selected image.
 71. A method of upgrading a first systemconfigured for taking a plurality of images of the gemstone and usingthem for generating an original 3D model of an external surface of agemstone, in order to provide a second system for producing an improved3D model of said external surface of the gemstone, which is moreaccurate than the original 3D model; said method comprising the stepsof: dd) adding to said first system a second illumination system and asecond imaging device configured for imaging, after said plurality ofimages have been taken and said original 3d model has been generated, anarea of each junction selected from one or more junctions, whoselocation is determined using the original 3D model, said area includingin addition to said junction only adjacent portions of its associatedfacets and edges disposed adjacent the junction, said secondillumination system being configured for providing illuminationconditions different from those, at which said plurality of images weretaken, and providing such contrast between adjacent facets as allow todistinguish an edge therebetween; and ee) adding computing capabilityfor: viii) analyzing images taken by said second imaging system toobtain information regarding the cut gemstone at said area; ix) usingsaid information for obtaining said improved 3D-model of the gemstone.72. The method according to claim 71, wherein said second imaging deviceis configured for said imaging under an at least one of the following: amagnification higher than that provided by provided by an imaging devicewith which the original 3D image has been obtained; a resolution higherthan that provided by provided the imaging device with which theoriginal 3D image has been obtained; or a depth of focus lower than thatprovided by the imaging device with which the original 3D image has beenobtained.
 73. The method according to claim 72, wherein the first systemcomprises at least one first gemstone holder with a first gemstonemounting surface for mounting a gemstone thereon, said first holderbeing configured to be mounted on said stage base, and wherein saidmethod further comprises replacing said at least one first holder withat least one second holder having a second gemstone supporting surfaceso as to allow an access of an illumination source to a space betweensaid second gemstone supporting surface and the stage base.
 74. A kitfor upgrading a first system configured for taking a plurality of imagesof the gemstone and using them for generating an original 3D model of anexternal surface of a gemstone, in order to obtain a second system forproducing an improved 3D model of said external surface of a gemstone,which is more accurate than the original 3D model, said first systemcomprising a first set of gemstone holders each having a first gemstonemounting surface, a first illumination source and a first imagingdevice, and a computer system configured to produce said original 3Dmodel, said kit comprising: at least one second illumination sourcedifferent from the first illumination device and a second imaging devicedifferent from the first imaging device, the second illumination sourceand the second imaging device being configured for imaging, after saidplurality of images have been taken and said original 3d model has beengenerated, an area of each junction selected from one or more junctions,whose location is determined using the original 3D model, said areaincluding in addition to said junction its associated facets and edgesdisposed adjacent the junction, said imaging being performed underillumination conditions different from those, at which said plurality ofimages were taken, and providing such contrast between adjacent facetsas to allow to distinguish an edge therebetween; a capability providedto said computer system, of analyzing results of said imaging to obtaininformation regarding the gemstone at said area; and using saidinformation for producing the improved 3D-model, which is more accuratethan the original 3-D model; and, optionally, a second set of gemstoneholders each having a second gemstone mounting surface and beingconfigured for mounting on a stage base such so as to allow an access ofsaid second illumination source to a space between said second gemstonemounting surface and the stage base.